Washington (CNN) -- A hoax mayday call that launched a massive search off the coast of New Jersey last week may be linked to a similar call made last month nearly 1,500 miles away off Texas, authorities said Wednesday.
At a news conference in New York, Coast Guard investigators said that in both cases the callers reported their boats were sinking and used similar key words and phrases, leading authorities to believe the calls could have come from the same individual.
On May 20, rescuers searched for 36 hours in waters off the coast of Galveston, Texas, and found nothing after a distress call reporting six people stranded in the water, Chief Warrant Officer Lionel Bryant told CNN.
On June 11, a distress call reporting a yacht explosion prompted a massive rescue effort in the water near New Jersey. The call was determined to be fake after no evidence of a boat was found.
Officials initially classified the Texas call as unresolved because the Coast Guard could not eliminate the possibility that the distress call came from a vessel in the water. But a Houston television reporter alerted the Coast Guard's New York office to similarities in the two cases, and that led authorities to take a closer look.
"By no means is it a guarantee that this was the same individual that made both calls. We're analyzing the voices on both calls," Coast Guard Capt. Gregory Hitchen told reporters.
In both instances, the caller described his boat as "taking on water" rather than sinking, described the people on board his boat as "souls," said victims were in orange life rafts and used a similar speaking pattern, Hitchen said. Investigators said the calls in both cases seem to have originated from land, he added.
The Coast Guard said the estimated cost of the rescue operation in the New Jersey case was $300,000.
The agency is relying on the media and tips from the public to find the callers because current technology isn't capable of allowing investigators to pinpoint exactly where the calls came from.
But officials are hoping that the person responsible for the false calls finds it difficult to keep quiet.
"They do brag about it in certain cases," Hitchen said.
More than 100 calls have come in to a tip line, Coast Guard Investigative Service Special Agent Michael Donnelly told reporters Wednesday.
Authorities released audio excerpts from both of the mayday calls.
In the New Jersey incident, a male voice is heard saying, "We have 21 souls on board, 20 in the water right now. I have three deceased on board, nine injured because of the explosion we've had. I'm in three feet of water on the bridge. I'm going to stay by the radio as long as I can before I have to go overboard."
In the Texas case, the voice says, "We're about probably 2 miles from the channel and we are taking on water." The caller was unable to give an exact location in either call.
Anyone convicted of making a false mayday call to the Coast Guard would face six years in prison and a $250,000 fine, but finding such perpetrators has proven difficult for authorities. Investigations rarely have led to an arrest or conviction.
There were 60 reported hoax calls in the New York region in 2011, but since 2004 only four people have been convicted for making false distress claims.
Authorities don't believe the false calls are terrorism-related.
CNN's Mike Ahlers contributed to this report.